Vehicle-mounted ignitor

Abstract

A circuit for supplying an oscillation suppress current is provided between a collector terminal and gate electrode of a main IGBT. The current supply circuit comprises a resistor and a diode which are connected in series. A bypass MOSFET is connected between the series connection and the emitter terminal. No semiconductor element having different temperature characteristics is provided in the current supply circuit.

What is claimed is:  
     
       1. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less by controlling the potential on a control electrode of said semiconductor device; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device having a higher potential,  
       wherein said current supply circuit has at least a resistor and potentially connects said main terminal having the higher potential to said control terminal without interposing any semiconductor switching element therebetween.  
     
     
       2. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device having a higher potential,  
       wherein said current supply circuit connects said main terminal having the higher potential to said control terminal via a series connection of a resistor and a diode.  
     
     
       3. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less by controlling the potential on a control electrode of said semiconductor device; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device having a higher potential,  
       wherein said ignitor is provided with a bypass circuit which connects said current supply circuit to one of said pair of main terminals, having a lower potential when a signal for driving said semiconductor element is not input to said control terminal.  
     
     
       4. The vehicle-mounted ignitor as defined in  claim 3 , wherein said bypass circuit comprises a switching element which is connected between the current supply circuit and one of said pair of main terminals having a lower potential and said ignitor is provided with a circuit which turns on the switching element when a signal for driving said semiconductor element is not input to said control terminal. 
     
     
       5. The vehicle-mounted ignitor as defined in  claim 3 , further comprising an inverter circuit for reversing a signal input to said control terminal and a first switching element which is driven by the output from the inverter circuit. 
     
     
       6. The vehicle-mounted ignitor defined in  claim 5 , wherein said inverter circuit comprises a second switching element having a pair of electrodes and a drive electrode; and a resistor which is connected between one of said pair of electrodes of said second switching elements and one of said pair of electrodes having a higher potential; said series connection being connected to the control electrode of said first switching element as an output terminal of said inverter circuit. 
     
     
       7. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less by controlling the potential on a control electrode of said semiconductor device; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device having a higher potential,  
       wherein said current supply circuit comprises a series circuit of at least a resistor and a diode, which is connected in a direction toward said control electrode from said main terminal having a higher potential; and a constant voltage element for restricting the potential on the series connection between said resistor and said diode to a predetermined value.  
     
     
       8. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device, having a higher potential,  
       wherein said current supply circuit supplies a current to said control terminal from said main terminal having a higher potential for controlling the current to a predetermined value.  
     
     
       9. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device, having a higher potential,  
       wherein said current supply circuit supplies a current to said control terminal from said main terminal having a higher potential when said voltage of said main terminal having a higher potential is lower than a predetermined value and restricts the supply of the current to said control terminal when the voltage of said main terminal is higher than the predetermined value.  
     
     
       10. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current restricting circuit for restricting a main current flowing through said semiconductor device to a predetermined value or less; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device having a higher potential,  
       wherein said semiconductor element, said current restricting circuit and said current supply circuit are incorporated within the range of the diameter of the ignition coil unit as a chip.  
     
     
       11. A vehicle-mounted ignitor comprising: 
       a primary coil of an ignition coil and an insulated gate type semiconductor device which are connected in series with a direct current source;  
       an ignition plug connected to a secondary coil of the ignition coil, to which a higher voltage generated across the secondary coil by switching of said semiconductor device is applied;  
       a current flowing through said semiconductor device to a predetermined value or less by controlling the potential on a control electrode of said semiconductor device; and  
       a current supply circuit for supplying said control electrode with a current from one of a pair of main terminals of said semiconductor device having a higher potential,  
       wherein said current supply circuit is configured to connect said one of said main terminals having a higher potential to said control electrode via not switching element, but a resistor, said system further including an ignition coil unit comprising said semiconductor element, said current restricting circuit and said current supply circuit which are incorporated as a chip; a connecting terminal of said ignition plug which is provided at one end of the ignition coil unit; and an ignition plug which is connected to said connecting terminal, said ignition coil unit and ignition plug being integrated with each other and being embedded in the engine wall so that said ignition plug is exposed within a combustion chamber.